Glucose-based polysaccharides and their derivatives can be of potential industrial application.
Cellulose is a typical example of such a polysaccharide and is comprised of beta-1,4-D-glycosidic linkages of hexopyranose units. Cellulose is used for several commercial applications such as in manufacture of fibers and films (cellophane). Cellulose for industrial applications is derived from wood pulp. Solutioning of wood pulp is a difficult procedure. For cellophane production the most commonly used process for dissolution of cellulose is the ‘viscose process’ where the cellulose is converted to cellulose xanthate made by treating a cellulose compound with sodium hydroxide and carbon disulfide. The cellulose xanthate solution is extruded into a coagulation bath, where it is regenerated upon coagulation to form a cellulose film. Cellophane film has several desirable attributes like clarity, barrier to oxygen, mechanical strength etc. which has resulted in its application as a packaging film. However the disadvantage is the use of this viscose process in cellophane manufacture, which involves toxic chemicals and significant environmental costs.
Amongst polysaccharide polymers, glucan polymers, with alpha-1,3-glycoside linkages, have been shown to possess significant advantages. U.S. Pat. No. 7,000,000 disclosed preparation of a polysaccharide fiber comprising a polymer with hexose units, wherein at least 50% of the hexose units within the polymer were linked via alpha-1,3-glycoside linkages, and a number average degree of polymerization of at least 100. A glucosyltransferase enzyme from Streptococcus salivarius (gtfJ) was used to produce the polymer. The polymer alpha-1,3-glucan was acetylated in order to render the polymer soluble in the spinning solvent. The acetylated polymer was then dissolved in a mixture of trifluoro-acetic acid and dichloromethane. From this solution continuous, strong, fibers of glucan acetate were spun. These glucan acetate fibers can subsequently be de-acetylated to form fibers composed of alpha-1,3-glucan.
It would be desirable to make films composed of a polysaccharide alpha-1,3-glucan polymer which have properties comparable to cellophane, without the need for a derivatization step. In addition, elimination of the use of hazardous chemicals such as carbon disulfide required for xanthation of cellulose would be desirable.